ABSTRACT
Astronomical tables provide the means for computing the celestial positions of the Sun, Moon, and planets at any time, based on a self-consistent theory; and ephemerides provide a continuous reference system of observations to meet practical requirements by giving daily geocentric positions of the Sun, Moon, and planets, generally deduced from particular astronomical tables. They are two indispensable mediators between astronomical observation and theory (consisting of a hypothesis on planetary motion and fundamental orbital parameters), the four components thus forming a synthesis. The confrontation with one another within this synthesis has, throughout the history of astronomy, been the ultimate source for the development of this observational science. An example is Johannes Kepler’s (1571-1630) search for a theory in his Astronomia nova (1609), using Erasmus Reinhold’s (1511-1553) Prutenic Tables of 1551, based on the Copernican theory, several late-sixteenth-century ephemerides, and Tycho Brahe’s (1546-1601) observations.
